Rescuing macrophage normal function in spinal cord injury with embryonic stem cell conditioned media

Abstract

BackgroundMacrophages play an important role in the inflammatory responses involved with spinal cord injury (SCI). We have previously demonstrated that infiltrated bone marrow-derived macrophages (BMDMs) engulf myelin debris, forming myelin-laden macrophages (mye-Mϕ). These mye-Mϕ promote disease progression through their pro-inflammatory phenotype, enhanced neurotoxicity, and impaired phagocytic capacity for apoptotic cells. We thus hypothesize that the excessive accumulation of mye-Mϕ is the root of secondary injury, and that targeting mye-Mϕ represents an efficient strategy to improve the local inflammatory microenvironment in injured spinal cords and to further motor neuron function recovery. In this study, we administer murine embryonic stem cell conditioned media (ESC-M) as a cell-free stem cell based therapy to treat a mouse model of SCI.ResultsWe showed that BMDMs, but not microglial cells, engulf myelin debris generated at the injury site. Phagocytosis of myelin debris leads to the formation of mye-Mϕ in the injured spinal cord, which are surrounded by activated microglia cells. These mye-Mϕ are pro-inflammatory and lose the normal macrophage phagocytic capacity for apoptotic cells. We therefore focus on how to trigger lipid efflux from mye-Mϕ and thus restore their function. Using ESC-M as an immune modulating treatment for inflammatory damage after SCI, we rescued mye-Mϕ function and improved functional locomotor recovery. ESC-M treatment on mye-Mϕ resulted in improved exocytosis of internalized lipids and a normal capacity for apoptotic cell phagocytosis. Furthermore, when ESC-M was administered intraperitoneally after SCI, animals exhibited significant improvements in locomotor recovery. Examination of spinal cords of the ESC-M treated mice revealed similar improvements in macrophage function as well as a shift towards a more anti-inflammatory environment at the lesion and parenchyma.ConclusionsThe embryonic stem cell conditioned media can be used as an effective treatment for SCI to resolve inflammation and improve functional recovery while circumventing the complications involved in whole cell transplantation.

Anti-Inflammatory Mechanism of Neural Stem Cell Transplantation in Spinal Cord Injury

“…Nemeth et al observed that transplantation of human MSCs after SCI promoted functional recovery and modified the inflammatory environment by skewing macrophages into the anti-inflammatory M2 phenotype [ 47 , 48 ]. In addition, our previous data showed that ESC-conditioned media can effectively reduce lipid accumulation, promote an M2-like state and improve functional recovery after spinal cord injury [ 49 ]. In the present study, NSC transplantation improved functional recovery following SCI possibly due to the downregulation of M1 macrophages.…”

Anti-inflammatory effect of stem cells against spinal cord injury via regulating macrophage polarization

“…109 Transplanted ESCs may form teratomas, which are constituted by cells from endodermal, mesodermal, and ectodermal lineages. [110][111][112] Recently, Guo et al 113 show that ESC-conditioned media can effectively reduce lipid accumulation, promote an M2-like state, and improve functional recovery after SCI. ESC-conditioned medium is sufficient to promote functional recovery in a murine model of SCI and avoids teratoma formation.…”

Evaluation of the effect of BMSCs condition media and methylprednisolone in TGF-β expression and functional recovery after an acute spinal cord injury

“…Some studies considered the appropriate time for drug injection 8 hours after the spinal cord injury (16). Some experimental studies have not considered the use of high-dose MP for improvement of acute SCI (17,18). Our results revealed that the application of appropriate MP dose after SCI has positive effects on preventing infl ammation and cavity size in spinal cord.…”

“…Reverse transcription was carried out Step OnePlus™ Real-Time PCR System (Applied Biosystems, USA) with Syber Green PCR Master Mix (Applied Biosystems, USA) based on the company's guidelines under the following conditions: initial denaturation at 95˚C, denaturation at 95˚C for 30sec, annealing at 56˚C for 45sec, extension at 72˚C for 45sec and a fi nal polymerization at 72˚C for 10min.The primer sequences are brief in table 1. We applied the comparative a Ct method for gene target expression analysis (2ΔΔCt) (17). All samples normalized with GAPDH level, as the loading control (16).…”